Momotarō is the pet dog of Saho Shimatani, making recurring appearances throughout the anime. He is a four-legged canine with a yellowish-brown coat, resembling a shiba inu, and is often seen wearing a collar. As a domestic animal rather than a fighter, his background is tied to the Shimatani household, where he lives as a loyal companion. His personality is that of a typical devoted pet; he is protective of his owner and the territory he considers home. When a Scorpion-Bone attacks, Momotarō bravely attempts to defend the area on his own, motivated by instinct to guard those he cares about. However, he is outmatched and must be rescued by Shougo Ryuujin, highlighting his limitations as an ordinary animal in a world of powerful Bone Fighters. His role in the story is primarily that of Saho's pet, providing a grounding domestic presence and occasionally participating in small-scale conflicts where his courage outpaces his actual ability. His key relationship is with Saho, his owner, and his interactions with the main cast often occur in the context of defending her or the home. Momotarō does not undergo significant character development, remaining a consistent and simple supporting figure throughout the series. His notable abilities are those of a typical dog, including keen senses, loyalty-driven bravery, and a protective nature, but he does not possess any supernatural or combat-oriented skills relevant to the main battles.